JRuby support

This gem is unusable on anything but CRuby mostly because it uses the following CRuby-specific features:

lib/error_highlight/base.rb  (4 usages found)
    59           RubyVM::AbstractSyntaxTree.of(loc, keep_script_lines: true)
    70     when RubyVM::AbstractSyntaxTree::Node, Prism::Node
    93     node_id = RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(location)

We could fix this for JRuby in one of two ways:

• Switch to the Prism gem where possible. I'm not sure if it can help us get a specific AST node from a backtrace element without reparsing, though. cc @kddnewton
• Use JRuby-specific methods to access similar internal code structures.

It would be nice if JRuby users could benefit from the features of this gem.

Inizia dai quattro utilizzi specifici di CRuby elencati in lib/error_highlight/base.rb, in particolare le chiamate a RubyVM::AbstractSyntaxTree e il ramo Prism::Node. Verifica se Prism può fornire le informazioni AST necessarie dal backtrace o se sono necessari metodi specifici di JRuby, quindi verifica che le funzionalità di evidenziazione delle eccezioni del gem funzionino su JRuby.